1. Field of the Invention
The present invention relates to an image processing method. More particularly, the present invention relates to an image processing method, which may individually process an image of each single pixel unit.
2. Description of Related Art
Image processing includes adjustment of image information such as color and brightness of an image. With a growing demand in high quality digital image, digital image processing technique is being rapidly developed. Regardless of how dark or how bright a digital image is, contrast, brightness and color saturation etc. of the digital image may be improved after the image processing.
Presently, a commonly used image processing method for enhancing image contrast and adjusting image brightness is based on a histogram equalization technique. In brief, the histogram equalization technique is to redistribute brightness values of all pixels of a whole image, such that the brightness and the contrast of the whole image may be distributed more evenly. In other words, based on the histogram equalization technique, a relatively dark image or a relatively bright image may be modified to obtain a normal color gamut. For example, the relatively dark image may gain some bright pixels after the histogram equalization is performed, and the relatively bright image may gain some dark pixels after the histogram equalization is performed.
However, though the image contrast may be improved, the image brightness may be adjusted and the color saturation problem may be solved based on the histogram equalization technique, such technique may lead to a distortion of image hue and color saturation. Moreover, the histogram equalization technique requires performing calculation on a large amount of data, and therefore additional frame memory is required, which may further increase complexity and cost of hardware.
Accordingly, based on U.S. Pat. No. 6,721,000, an image signal to be input to a single pixel is transformed into a YUV color space, and the elements U and V representing chrominance thereof may be multiplied with a factor S(Y,U,V) to increase the color saturation. However, if this method is applied to the pixel with high color saturation, a clipping phenomenon may be occurred to a portion of the image information, and original relatively fine solution of the image may be lost. Therefore, in the SID2004 conference, an image processing method for mitigating the clipping phenomenon of the image information is disclosed by Philips Research Laboratories in an article entitled “More Realistic Colors from Small-Gamut Mobile Displays”. However, this method is performed based on adding add white color to the original image data, such that the image processed by this method may have a phenomenon of partial white.
Therefore, the above image processing methods all have their shortcomings, in which true presentation of original image hue cannot be achieved while simultaneously improving the color saturation and contrast of the image. If a simple image processing technique may be provided for compensating the color saturation and contrast of the image, and meanwhile the image hue remains unchanged, the image processing technique may be greatly improved.